seriously concerned

Jayde • My name is Jayde, I have a wonderful husband and beautiful son, I am expecting our 2nd child in July 2017 ❤️
Hey guys, I need some help. I am 7 weeks and I am experiencing some light bleeding that's dark colored. I haven't had ANY SYMPTOMS until today, no cramping no sporting or anything it pretty much came out of no where but I have been on my feet a lot the last couple of days. 
I contacted my doctor and she said that I need to rest and not do anything strenuous. But she said that there's nothing to worry about unless the cramps get worse (I haven't had any since this morning) and then I should go to the emergency room.
I'm terrified, sad, and sick to my stomach knowing that it could be the worst. Has anyone else experienced this?